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Aedes aegypti abundance, larval indices and risk for dengue virus transmission In Kinondoni district, Tanzania
(BMC, 2022) Ngingo, Baraka L; Mboera, Leonard E. G; Chengula, Augustino; Machelle, Ines; Makange, Mariam R; Msolla, Michael; Mwanyika, Gaspary O; Rugarabamu, Sima; Misinzo, Gerald
Background: Tanzania has experienced periodic dengue outbreaks with increased incidence since 2010. However, there is limited information on vector dynamics and transmission risk in most parts of the country. This study was conducted to determine Aedes mosquito abundance, larval indices and dengue virus infection rate as risk indicators for DENV transmission in Kinondoni district, Dar es Salaam, Tanzania. Methods: A cross-sectional study was conducted in three wards of Kinondoni district in Tanzania between Decem- ber 2019 and January 2020. In each ward, three streets were randomly selected for adult and immature mosquito sampling. The adult mosquitoes were collected using Mosquito Magnet traps, while mosquito larvae and pupae were inspected in water-holding containers in the selected household compounds. The detection of dengue virus (DENV) in female Aedes mosquitoes was done using a one-step reverse transcription–polymerase chain reaction (RT–PCR) method. Results: Of the 1416 adult female mosquitoes collected, Ae. aegypti accounted for 16.8% (n = 238). A total of 333 water-holding containers were inspected and 201 (60.4%) had at least an Aedes larvae or pupae. Water-holding containers supporting the breeding of Aedes larvae and pupae included discarded car tires, flowerpots and small and large plastic containers. The overall House Index, Container Index and Breteau Index were 55.1%, 60.4% and 114.2, respectively. None of the 763 female Aedes mosquitoes tested by RT–PCR was found to be infected with DENV. Conclusion: The presence and abundance Ae. aegypti mosquitoes and the large proportion of water-holding con- tainers infested with the mosquito larvae and pupae put residents of Kinondoni district at high risk of DENV trans- mission. Our findings emphasize the need for continuous mosquito vector surveillance and control to prevent the possibility of future DENV outbreaks in Tanzania.
African animal trypanosomiasis: a systematic review on prevalence, risk factors and drug resistance in Sub-Saharan Africa
(Oxford University Press on behalf of Entomological Society of America, 2022) Okello, Ivy; Mafie, Eliakunda; Eastwood, Gillian; Nzalawahe, Jahashi; Mboera, Leonard E. G.
African animal trypanosomiasis (AAT) a parasitic disease of livestock in sub-Saharan Africa causing tremen- dous loses. Sub-Saharan continental estimation of mean prevalence in both large and small domestic animals, risk factors, tsetse and non-tsetse prevalence and drug resistance is lacking. A review and meta-analysis was done to better comprehend changes in AAT prevalence and drug resistance. Publish/Perish software was used to search and extract peer-reviewed articles in Google scholar, PubMed and CrossRef. In addition, ResearchGate and African Journals Online (AJOL) were used. Screening and selection of articles from 2000–2021 was per- formed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Articles 304 were retrieved; on domestic animals 192, tsetse and non-tsetse vectors 44, risk factors 49 and trypanocidal drug resistance 30. Prevalence varied by, host animals in different countries, diagnostic methods and species of Trypanosoma. Cattle had the highest prevalence with Ethiopia and Nigeria leading, T. congolense (11.80– 13.40%) and T. vivax (10.50–18.80%) being detected most. This was followed by camels and pigs. Common di- agnostic method used was buffy coat microscopy. However; polymerase chain reaction (PCR), CATT and ELISA had higher detection rates. G. pallidipes caused most infections in Eastern regions while G. palpalis followed by G. mortisans in Western Africa. Eastern Africa reported more non-tsetse biting flies with Stomoxys leading. Common risk factors were, body conditions, breed type, age, sex and seasons. Ethiopia and Nigeria had the highest trypanocidal resistance 30.00–35.00% and highest AAT prevalence. Isometamidium and diminazene showed more resistance with T. congolense being most resistant species 11.00–83.00%.
Anti-TB drug resistance in Tanga, Tanzania: A cross sectional facility-base prevalence among pulmonary TB patients
(2015-11) Hoza, A. S.; Mfinanga, S. G. M.; Konig, B.
Objective: To determine the prevalence and risk factors associated with drug resistance tuberculosis (TB) at facility-base level in Tanga, Tanzania. Methods: A total of 79 Mycobacterium tuberculosis (MTB) isolates included in the study were collected from among 372 (312 new and 60 previously treated) TB suspects self-referred to four TB clinics during a prospective study conducted from November 2012 to January 2013. Culture and drug susceptibility test of the isolates was performed at the institute of medical microbiology and epidemiology of infectious diseases, University hospital, Leipzig, Germany. Data on the patient's characteristics were obtained from structured questionnaire administered to the patients who gave informed verbal consent. Unadjusted bivariate logistic regression analysis was performed to assess the risk factors for drug resistant-TB. The significance level was determined at P < 0.05. Results: The overall proportions of any drug resistance and MDR-TB were 12.7% and 6.3% respectively. The prevalence of any drug resistance and MDR-TB among new cases were 11.4% and 4.3% respectively, whereas among previously treated cases was 22.2% respectively. Previously treated patients were more likely to develop anti-TB drug resistance. There was no association between anti-TB drug resistances (including MDRTB) with the risk factors analysed. Conclusions: High proportions of anti-TB drug resistance among new and previously treated cases observed in this study suggest that, additional efforts still need to be done in identifying individual cases at facility-base level for improved TB control programmes and drug resistance survey should continuously be monitored in the country.
Antibiogram and diversity of extended-spectrum beta-lactamase genes in scavenging local chicken in Morogoro municipality, Tanzania
(Excellent publishers, 2020-02-20) Armah, Emmanuel Odartei; Tuntufye, Huruma Nelkiwe
The poultry industry, especially chicken production has in recent times faced a major set-back due to devastating effects of APEC Extended Spectrum Beta- Lactases (ESBL) producing organisms. This research aimed at investigating antimicrobial susceptibility profile and diversity of ESBL producing avian pathogenic Escherichia coli(APEC) among fecal cloacal swaps of scavenging local chickens based on the various housing systems. The APEC isolates were determined by virulence factor profiling and by Kirby-Baeur disc diffusion, 42% of the APEC isolates were found to be ESBL producers. Of the ESBL isolates, 87.5% were resistant to nalidixc acid, 37.5% were resistant to cefotaxime, Trimethroprim-Sulfamethoxazole, augmentnin and cephalothin, 25% were resistant to Ceftriaxone whiles no isolate was resistant to Imipenem, gentamycin and ciprofloxacin. On screening, a total of 32 beta-lactamase genes were found amongst these isolates, all of these isolates harbored the blaTEM gene.Semi-intensively kept chickens harbored more ESBL genes and in more diverse forms than the extensively kept ones.
Antibiogram of avian pathogenic escherichia coli in scavenging local chicken in Morogoro, Tanzania
(2021-04) Armah, Emmanuel Odartei
Avian pathogenic Escherichia coli (APEC) is responsible for the annual million-dollar loss in the poultry industry worldwide. This research aimed at investigating the occurrence and antimicrobial pattern of APEC among scavenging local chickens. A total of 400 cloacal and oropharyngeal swabs were obtained, out of which 192 Escherichia coli were isolated. By use of virulence factor profiling, these 192 samples were screened for the presence of 16 virulence factors by multiplex PCR. All 192 samples harbored at least one of the 16 virulence genes and 19 of them carried at least four, making them APEC. The virulence traits ibeA, iss, traT and chuA were observed to lead the chart with percentages of 84.21, 78.95, 63.16 and and 52.63 respectively. In the pathogenesis of APEC, Iron acquisition, serum resistance, toxins and invasins were found to be very significant (P<0.05). The antimicrobial sensitivity testing, 10.52% of the strains showed multi-drug resistance. All the isolates were sensitive to gentamycin and imipenem drugs whiles none of them were sensitive to cephalothin. Occurrence of virulence strains of APEC in Morogoro region of Tanzania is alarming.
Antigenic differences among porcine circovirus type 2 strains, as demonstrated by the use of monoclonal antibodies
(Journal of General Virology, 2008) Lefebvre, D. J.; Costers, S.; Doorsselaere, J. V.; Misinzo, G.; Delputte, P. L.; Nauwynck, H. J.
This study examined whether antigenic differences among porcine circovirus type 2 (PCV-2) strains could be detected using monoclonal antibodies (mAbs). A subtractive immunization protocol was used for the genotype 2 post-weaning multisystemic wasting syndrome (PMWS)-associated PCV-2 strain Stoon-1010. Sixteen stable hybridomas that produced mAbs with an immunoperoxidase monolayer assay (IPMA) titre of 1000 or more to Stoon-1010 were obtained. Staining of recombinant PCV-2 virus-like particles demonstrated that all mAbs were directed against the PCV-2 capsid protein. Cross-reactivity of mAbs was tested by IPMA and neutralization assay for genotype 1 strains 48285, 1206, VC2002 and 1147, and genotype 2 strains 1121 and 1103. Eleven mAbs (9C3, 16G12, 21C12, 38C1, 43E10, 55B1, 63H3, 70A7, 94H8, 103H7 and 114C8) recognized all strains in the IPMA and demonstrated neutralization of Stoon-1010, 48285, 1206 and 1103, but not VC2002, 1147 and 1121. mAbs 31D5, 48B5, 59C6 and 108E8 did not react with genotype 1 strains or had a reduced affinity compared with genotype 2 strains in the IPMA and neutralization assay. mAb 13H4 reacted in the IPMA with PMWS-associated strains Stoon-1010, 48285, 1206 and VC2002, and the porcine dermatitis and nephropathy syndrome-associated strain 1147, but not with reproductive failure-associated strains 1121 and 1103. mAb 13H4 did not neutralize any of the tested strains. It was concluded that, despite the high amino acid identity of the capsid protein (¢91 %), antigenic differences at the capsid protein level are present among PCV-2 strains with a different genetic and clinical background.
Antimicrobial resistance pattern of escherichia coli isolates from small scale dairy cattle in Dar es Salaam, Tanzania
(MDPI, 2022-07-21) Azabo Rogers R.; Mshana Stephen E.; Matee Mecky; Kimera Sharadhuli I.
In Tanzania, information on antimicrobial resistance in small-scale dairy cattle is scarce. This cross-sectional study was conducted to determine the different levels and pattern of antimicrobial resistance (AMR), in 121 Escherichia coli isolated from rectal swab of 201 apparently healthy small-scale dairy cattle in Dar es Salaam, Tanzania. Isolation and identification of E. coli were carried out using enrichment media, selective media, and biochemical tests. Antimicrobial susceptibility testing was carried out using the Kirby–Bauer disk diffusion method on Mueller-Hinton agar (Merck), according to the recommendations of Clinical and Laboratory Standards Institute (CLSI). Resistance was tested against ampicillin, gentamicin, chloramphenicol, trimethoprim-sulfamethoxazole, tetracycline, nalidixic acid, ciprofloxacin and cefotaxime. Resistance to almost all antimicrobial agents was observed. The agents to which resistance was demonstrated most frequently were ampicillin (96.7%), cefotaxime (95.0%), tetracycline (50.4%), trimethoprim-sulfamethoxazole (42.1%) and nalidixic acid (33.1%). In this case, 20 extended-spectrum beta-lactamases (ESBLs) producing E. coli were identified. 74.4% (90/121) of the isolates were Multidrug resistant (MDR), ranging from a combination of three to 8 different classes. The most frequently observed phenotypes were AMP-SXT-CTX with a prevalence of 12.4%, followed by the combination AMP-CTX with 10.7% and TE-AMP-CTX and NA + TE + AMP + CTX with 8.3% each. The high prevalence and wide range of AMR calls for prudent antimicrobial use.
Antimicrobial use in cattle and poultry production on occurrence of multidrug resistant Escherichia coli. A systematic review with focus on sub-Saharan Africa
(Frontiers, 2022-10-24) Azabo, Rogers; Dulle, Frankwell; Mshana, Stephen E.; Matee, Mecky; Kimera, Sharadhuli
Antimicrobial use in livestock production has been linked to antimicrobial resistance (AMR) worldwide; however, optimization of their use has been considered an important strategy in dealing with it. The aims of this study were as follows: (a) to assess the literature on antimicrobial usage (practices, frequency, class, type) in cattle and poultry production with regard to resistance in Escherichia coli (E. coli) including multidrug resistance (MDR) (b) summarize evidence for quantitative (volumes of active antimicrobial ingredients) and quality (identify and quantify active ingredient) and (c) to identify data gaps. Peer reviewed literature search was conducted by querying two online databases: PubMed and Google scholar from November 15, 2018 to February 2019. The inclusion criteria for eligibility were articles: published in English between 2008 and 2018, including poultry (chicken) or cattle or both, E. coli bacteria of choice, antimicrobial use on farms, quantitative data and quality of antimicrobial used. Microsoft Excel was used for data extraction and Rayyan software for eligibility studies. The search retrieved 1,446 probable articles including those from the reference list of significant papers, of which twenty-four articles remained on full text review with more than a third of the studies being conducted in Nigeria. Farm surveys and antimicrobial sales were identified as the main sources of data and the mean quantities of antimicrobials based on sales data were 23,234, 41,280.87, and 1,538,443 kg of the active ingredient in Nigeria, Zambia and South Africa, respectively. One study from Cameroon determined the quantities of active ingredients based on dose metrics while another study still from Cameroon mentioned the quality of antimicrobials. Tetracyclines, beta-lactams/aminoglycosides and fluoroquinolones were the most common classes of antimicrobials (antibiotics) used. Our review reveals a dearth of information in Sub- Saharan Africa on the quantity and quality of veterinary drugs and yet they play a role in the overall picture of antimicrobial resistance. This finding gives an opportunity in the area of focus for future research as far as resistance and multidrug resistance are concerned in food producing animals.
Assessment of antimicrobial consumption in food animals in Dar es Salaam, Tanzania
(Integrity Research Journals, 2021-10-13) Azabo, Rogers; Matee, Mecky; Kimera, Sharadhuli
Monitoring antimicrobial use in food-producing animals is one of the global strategies to tackle antimicrobial resistance. The purpose of the present study is to generate quantitative information on antimicrobial use pattern in Dar es Salaam, which will be used as an approach for future monitoring and surveillance of antimicrobial quantities consumed in food animals. A 3 years (2016-2018) retrospective survey of antimicrobial usage in food-producing animals in three selected districts of Dar es Salaam city, Eastern Tanzania was conducted. Data on antimicrobial quantities consumed was obtained from five purposively selected licensed veterinary pharmaceutical sales/outlet establishments in the study area, based on keeping detailed sales records for the study period.Data analysis was done using IBM SPSS version20. Animal population data were from FAO-Stat databaseused to extrapolate the quantity consumed in food animals to the entire population during the study period in Tanzania. The antimicrobials were analysed based on class, importance for human medicine and route of administration. The study revealed that 178.4 tonnes of antimicrobials (by weight of active ingredients) were consumed during the 3 years period, with an average of 59.5 ± 3.8 tonnes/year. The commonly consumed antimicrobials were tetracycline (44.4%), sulphonamides (20.3%), aminoglycosides (10.3%) and beta-lactams (7.4%). In relation to veterinary antimicrobial use importance to human medicine, 34.4% were of critically important antimicrobials; 4.1% reserve and 51% watch group according to AWaRe categorization of WHO. Most of the antimicrobials were administered orally. Overall,a mean of 7.44 ± 0.81 mg/PCU (population correction unit) was consumed by food-producing animals during the 3 years period. This finding can help improve monitoring and control of veterinary antimicrobial use in Dar es Salaam in particular and Tanzania in general by preserving the efficacy of antimicrobials for future animal and human generations.
Assessment of the Immunogenicity of a Novel Live Recombinant Rift Valley Fever arMP- 12ΔNSm21/384 Vaccine Candidate Following Intranasal Vaccination of Goats, Sheep and Calves in Tanzania
(2020-10) Nyundo, S; Adamson, E.K; Rowland, J; Palermo, P.M; Salekwa, L; Matiko, M.K; Bettinger, G.E; Wambura, P; Morrill, J.C; Sullivan, T.R; Watts, D.M
Background: Rift Valley fever virus (RVFV) is an arbovirus that causes morbidity and mortality in livestock and humans throughout Africa and in the Arabian Peninsula. Vaccines are effective for the prevention of Rift Valley fever (RVF) disease, but new and improved vaccines are needed to improve the safety of available vaccines. Also, non- invasive needle free vaccine delivery routes should be evaluated as an alternative for invasive routes of vaccination. Objective: The aim of this proof of concept study was to evaluate the safety and immunogenicity of a novel live attenuated recombinant RVFV arMP-12ΔNSm21/384 vaccine candidate following intranasal vaccination of goats, calves, and sheep in Tanzania. Methods: Healthy, 6-9 months old breeds of African sheep (Ovis aeris), goats (Capra aegagrus) and zebu calves (Bos taurus indicus) were used in this study. The animals were purchased from local livestock keepers in the Mvomero district of Morogoro region, Tanzania. Animals were seronegative to both RVFV and antibody at the time of use in the vaccine trials. Animals in the test group included 10 goats, 7 sheep and 10 calves that were vaccinated in the left nares with 50 μl each and 2 sheep were vaccinated with 100 μl each (50 μl each in the left and right nares) of a dose that contained 4 × 10 5 PFU/50 ul of arMP-12ΔNSm21/384 vaccine, while the control group, including 2 goats, 3 sheep and 2 calves that were injected in the left nares with 50 μl of phosphate buffered saline to serve as placebo controls. Rectal temperature was measured and blood samples were collected on day 14 and 0 before vaccination, and on days 3, 5, 7, 14, 21, 28 and 35 post vaccinations (PV). Serum samples collected on days 14 and 0 before vaccination were tested for RVFV neutralizing antibody by a plaque reduction neutralization test, and on days 3 and 5 PV, serum samples were tested for virus as possible evidence of a viremia in cell culture and weekly collected samples thereafter were tested for RVFV neutralizing antibody. Results: All animals were negative for RVFV neutralizing antibody at 14 and 0 days before vaccination and none of the animals had detectable viremia on days 3 and 5 PV, and none had clinical manifestations throughout the study. Among the 7 sheep, 10 goats, and 10 calves that received 50 μl each of the vaccine dose, 70% had the first detectable antibody on either day 5, 7 or 14 PV with titers ranging from 1:10 to 1:40. The 2 sheep that received the 100 μl each of the virus dose had the first detectable antibody on day 5 PV with a titer of 1:160. Subsequently, animals vaccinated with the 50 μl dose had antibody titers ranged from 1:10 to 640 on days 21, 28 and 35 PV, while those vaccinated with 100 μl maintained an antibody titer of 1:160 throughout the study. Moreover, there was no difference in the antibody titers between animal species p=0.34, although mean antibody titers of goats were highest. Conclusion: As a proof of concept studies, the findings demonstrated that intranasal vaccination is a promising route for vaccinating domestic ruminants with the RVFV arMP-12ΔNSm21/384 vaccine candidate. However, these preliminary results suggested that a larger dose of 4 × 10 5 PFU/100 ul of arMP-12ΔNSm21/384 vaccine needed to be administered to each animal to consistently elicit a robust immune response. Also, further studies are warranted using a larger number of domestic ruminants to confirm the immune response elicited by the larger dose of the vaccine administered via the intranasal route.
Bacteremia in critical care units at Bugando Medical Centre, Mwanza, Tanzania: the role of colonization and contaminated cots and mothers’ hands in cross-transmission of multidrug resistant Gram-negative bacteria
(Antimicrobial Resistance and Infection Control, 2020) Silago, V.; Kovacs, D.; Msanga, D. R.; Seni, J.; Matthews, L.; Oravcová, K.; Zadoks, R. N.; Lupindu, A. M.; Hoza, A. S.; Mshana, S. E.
Background: Multidrug resistance (MDR) is a major clinical problem in tertiary hospitals in Tanzania and jeopardizes the life of neonates in critical care units (CCUs). To better understand methods for prevention of MDR infections, this study aimed to determine, among other factors, the role of MDR-Gram-negative bacteria (GNB) contaminating neonatal cots and hands of mothers as possible role in transmission of bacteremia at Bugando Medical Centre (BMC), Mwanza, Tanzania. Methods: This cross-sectional, hospital-based study was conducted among neonates and their mothers in a neonatal intensive care unit and a neonatology unit at BMC from December 2018 to April 2019. Blood specimens (n = 200) were sub- cultured on 5% sheep blood agar (SBA) and MacConkey agar (MCA) plates. Other specimens (200 neonatal rectal swabs, 200 maternal hand swabs and 200 neonatal cot swabs) were directly inoculated on MCA plates supplemented with 2 μg/ml cefotaxime (MCA-C) for screening of GNB resistant to third generation cephalosporins, r-3GCs. Conventional biochemical tests, Kirby-Bauer technique and resistance to cefoxitin 30 μg were used for identification of bacteria, antibiotic susceptibility testing and detection of MDR-GNB and screening of potential Amp-C beta lactamase producing GNB, respectively. Results: The prevalence of culture confirmed bacteremia was 34.5% of which 85.5% were GNB. Fifty-five (93.2%) of GNB isolated from neonatal blood specimens were r-3GCs. On the other hand; 43% of neonates were colonized with GNB r- 3GCs, 32% of cots were contaminated with GNB r-3GCs and 18.5% of hands of neonates’ mothers were contaminated with GNB r-3GCs. The prevalences of MDR-GNB isolated from blood culture and GNB r-3GCs isolated from neonatal colonization, cots and mothers’ hands were 96.6, 100, 100 and 94.6%, respectively. Significantly, cyanosis (OR[95%CI]: 3.13[1.51–6.51], p = 0.002), jaundice (OR[95%CI]: 2.10[1.07–4.14], p = 0.031), number of invasive devices (OR[95%CI]: 2.52[1.08–5.85], p = 0.031) and contaminated cot (OR[95%CI]: 2.39[1.26–4.55], p = 0.008) were associated with bacteremia due to GNB. Use of tap water only (OR[95%CI]: 2.12[0.88–5.09], p = 0.040) was protective for bacteremia due to GNB. Conclusion: High prevalence of MDR-GNB bacteremia and intestinal colonization, and MDR-GNB contaminating cots and mothers’ hands was observed. Improved cots decontamination strategies is crucial to limit the spread of MDR- GNB. Further, clinical presentations and water use should be considered in administration of empirical therapy whilst awaiting culture results.
Batrachochytrium dendrobatidis detected in Kihansi spray toads at a captive breeding facility (Kihansi, Tanzania)
(Inter Research [Commercial Publisher], 2014-09-30) Makange, Mariam; Kulaya, Neema; Biseko, Emiliana; Kalenga, Parson; Mutagwaba, Severinus; Misinzo, Gerald
The chytrid fungus Batrachochytrium dendrobatidis (Bd) is the aetiological agent of amphibian chytridiomycosis, a disease associated with global amphibian population declines. In November 2012, mass mortalities of Kihansi spray toads Nectophrynoides asperginis were observed at the Kihansi captive breeding facility, located in the Udzungwa Mountains, Tanzania. Mortalities increased rapidly, and dead toads showed typical clinical signs of chytridiomycosis, including reddening of the skin that was especially evident on the toe pads. Treatment of toads with itraconazole rapidly reduced mortalities. Dead toads (n = 49) were collected and used to per- form Bd-specific polymerase chain reaction and subsequent nucleotide sequencing. All toads col- lected at the facility were positive for Bd. The obtained Bd 5.8S rRNA gene and flanking internal transcribed spacer regions (ITS1 and ITS2) were not 100% identical to any other Bd sequences in GenBank, but closely resembled isolates from Ecuador, Japan, USA, Brazil, Korea, and South Africa. To our knowledge, this is the first study reporting molecular characteristics of Bd isolated from the Udzungwa Mountains. Strict biosecurity measures at the breeding facility and in Kihansi spray wetlands where toads have been reintroduced have been implemented. Further studies on Bd epidemiology in the Udzungwa Mountains are recommended in order to understand its origin, prevalence, and molecular characteristics in wild amphibian populations. This will be important for conservation of several endemic amphibian species in the Udzungwa Mountains, which are part of the Eastern Arc Mountains, a global biodiversity hotspot.
Binding and entry characteristics of porcine circovirus 2 in cells of the porcine monocytic line 3D4/31
(2005) Misinzo, G.; Meerts, P.; Bublot, M.; Mast, J.; Weingartl, H. M.; Nauwynck, H. J.
Porcine circovirus 2 (PCV2) is associated with post-weaning multisystemic wasting syndrome and reproductive problems in pigs. Cells of the monocyte/macrophage lineage are important target cells in PCV2-infected pigs, but the method of binding and entry of PCV2 into these cells is unknown. Therefore, binding and entry of PCV2 to the porcine monocytic cell line 3D4/31 were studied by visualization of binding and internalization of PCV2 virus-like particles (VLPs) by confocal microscopy and chemical inhibition of endocytic pathways (clathrin- and caveolae-mediated endocytosis and macropinocytosis), followed by evaluation of the level of PCV2 infection. It was shown that PCV2 VLPs bound to all cells, with maximal binding starting from 30 min post-incubation. Bound PCV2 VLPs were internalized in 47±5?0% of cells. Internalization was continuous, with 70?5±9?7% of bound PCV2 VLPs internalized at 360 min post-incubation. Internalizing PCV2 VLPs co-localized with clathrin. PCV2 infection was decreased significantly by chemical inhibitors that specifically blocked (i) actin-dependent processes, including cytochalasin D (75?5±7?0% reduction) and latrunculin B (71?0±3?0% reduction), and (ii) clathrin-mediated endocytosis, including potassium depletion combined with hypotonic shock (50?2±6?3% reduction), hypertonic medium (56?4±5?7% reduction), cytosol acidification (59?1±7?1% reduction) and amantadine (52?6±6?7% reduction). Inhibiting macropinocytosis with amiloride and caveolae-dependent endocytosis with nystatin did not decrease PCV2 infection significantly. PCV2 infection was reduced by the lysosomotropic weak bases ammonium chloride (47?0±7?9% reduction) and chloroquine diphosphate (49?0±5?6% reduction). Together, these data demonstrate that PCV2 enters 3D4/31 cells predominantly via clathrin-mediated endocytosis and requires an acidic environment for infection.
Cell tropism and entry of porcine circovirus 2
(Elsevier, 2011-11-11) Nauwynck, H.J.; Sanchez, R.; Meerts, P.; Lefebvre, D.J.; Saha, D.; Huang, L.; Misinzo, G.
Porcine circovirus 2 (PCV2) may induce reproductive failure (return to oestrus, embryonic death, mum- mification, weak- and stillborn piglets) and postweaning multisystemic wasting syndrome (PMWS). Furthermore, it may modulate the immunity in such a way that it aggravates the outcome of many bacterial and viral infections. In the present paper, the cellular tropism and entry of PCV2 are described and linked with the pathological and clinical consequences.
Circulation of dengue serotype 1 viruses during the 2019 outbreak in Dar es Salaam, Tanzania
(Informa UK Limited, trading as Taylor & Francis Group., 2021) Mwanyika, Gaspary O.; Mboera, Leonard E. G.; Rugarabamu, Sima; Makange, Mariam; Sindato, Calvin; Lutwama, Julius J.; Paweska, Janusz T.; Misinzo, Gerald
Dengue is an important mosquito-borne viral disease in humans in tropical and subtropical countries. In 2019, a total of 6917 dengue cases were reported in Tanzania based on serological analysis. The aim of this study was to confirm the presence of dengue virus (DENV) and conduct its genetic characterization. A total of 191 serum samples were collected from the outpatients seeking care from health facilities in Kinondoni and Ilala districts between March and May 2019. All the samples were initially tested for the presence of non-structural protein 1 and anti-DENV immunoglobulin G (IgG) and IgM using a commercial OnSite Duo Dengue Ag-IgG/IgM rapid test. Of the 191 sera, 110 (57.6%) were DENV seropositive. The presence of DENV ribonucleic acid was confirmed in 18.2% of the seropositive sera by reverse transcription polymerase chain reaction (RT-PCR). The RT-PCR products were cleaned and partial sequences of DENV poly protein gene determined using dideoxynucleotide cycle sequencing followed by phylogenetic analysis. We present the occurrence of DENV serotype 1 (DENV-1) during the 2019 outbreak in Tanzania. The DENV-1 strains reported in the present study are highly identical and cluster with Asian DENV-1 strains indicating the possibility of intercontinental spread of DENV through globalization. We advocate for the need for molecular surveillance of dengue viruses during outbreaks to provide rapid evidence of the disease to guide public health interventions.
Climate change influences potential distribution of infected aedes aegypti co-occurrence with dengue epidemics risk areas in Tanzania
(PLOS, 2016) Mweya, Clement N; Kimera, Sharadhuli I; Stanley, Grades; Misinzo, Gerald; Mboera, Leonard E. G
Dengue is the second most important vector-borne disease of humans globally after malaria. Incidence of dengue infections has dramatically increased recently, potentially due to changing climate. Climate projections models predict increases in average annual tem- perature, precipitation and extreme events in the future. The objective of this study was to assess the effect of changing climate on distribution of dengue vectors in relation to epi- demic risk areas in Tanzania.
Comparative effectiveness of Aloe vera aqueous crude extracts and ivermectin for treatment of gastrointestinal nematodes infection in goats
(Tanzanina Veterinary Association, 2017) Ibrahim, H.; Nzalawahe, J.
The current study was undertaken to determine the effectiveness of Aloe vera aqueous crude extracts in comparison to Ivermectin in treatment of gastrointestinal nematodes infections in goats at Sokoine University of Agriculture in Morogoro. Goats were examined for GIT nematode infections using modified Mc master technique and those with EPG ≥ 150 were recruited for this trial. Furthermore, the recruited animals were randomly allocated into three groups (@10 animals) that included one control group and two experimental groups. The control group was left untreated while the remaining experimental groups were treated with Aloe Vera aqueous crude extracts and Ivermectin respectively. Faecal samples were collected at day of treatment (day 0) and days 14 and 21 post treatment. The effectiveness of the Aloe Vera and Ivermectin was assessed using Feacal Egg Count Reduction Test (FERT). The anthelmintic was considered to be effective when the calculated FECRT% was ≥ 95% and 95% Lower Confidence Limit (LCL) was ≥ 90%. The day 14 post treatment results of FERT% and LCL for Aloe vera were 97% and 74% while for Ivermectin were 96% and 69% respectively. However, the FERT% and LCL results at day 21 post treatment were 100% for both products. The findings of this study indicate that Aloe vera aqueous crude extracts were effective as Ivermectin in treatment of GIT nematodes infections in goats.
Correlation between the presence of neutralizing antibodies against porcine circovirus 2 (PCV2) and protection against replication of the virus and development of PCV2-associated disease
(2006-01-30) Meerts, P.; Misinzo, G.; Lefebvre, D.; Nielsen, J.; Bøtner, A.; Kristensen, C. S.; Nauwynck, H. J.
Background: In a previous study, it was demonstrated that high replication of Porcine circovirus 2 (PCV2) in a gnotobiotic pig was correlated with the absence of PCV2-neutralizing antibodies. The aim of the present study was to investigate if this correlation could also be found in SPF pigs in which PMWS was experimentally reproduced and in naturally PMWS-affected pigs. Results: When looking at the total anti-PCV2 antibody titres, PMWS-affected and healthy animals seroconverted at the same time point, and titres in PMWS-affected animals were only slightly lower compared to those in healthy animals. In healthy animals, the evolution of PCV2-neutralizing antibodies coincided with that of total antibodies. In PMWS-affected animals, neutralizing antibodies could either not be found (sera from field studies) or were detected in low titres between 7 and 14 DPI only (sera from experimentally inoculated SPF pigs). Differences were also found in the evolution of specific antibody isotypes titres against PCV2. In healthy pigs, IgM antibodies persisted until the end of the study, whereas in PMWS-affected pigs they quickly decreased or remained present at low titres. The mean titres of other antibody isotypes (IgG1, IgG2 and IgA), were slightly lower in PMWS-affected pigs compared to their healthy group mates at the end of each study. Conclusion: This study describes important differences in the development of the humoral immune response between pigs that get subclinically infected with PCV2 and pigs that experience a high level of PCV2-replication which in 3 of 4 experiments led to the development of PMWS. These observations may contribute to a better understanding of the pathogenesis of a PCV2- infection.
Demographic and spatio-temporal variation in human plague at a persistent focus in Tanzania
(Elsevier, 2006-10) Makundi, R.H; Davis, S; Machan"gu, R.S; Leirs, H
Human plague in the Western Usambara Mountains in Tanzania has been a public health problem since the first outbreak in 1980. The wildlife reservoir is unknown and eradication measures that have proved effective elsewhere in Tanzania appear to fail in this region. We use census data from 2002 and hospital records kept since 1986 to describe the temporal, spatial and demographic variation in human plague. A seasonal peak in cases occurs from December to February with the numbers of cases during this peak varying between 0 and 1150. Variation in incidence, calculated for each village as the mean number of cases per thousand inhabitants per year, indicates that human plague is concentrated around a group of three neighbouring, relatively isolated, high-altitude villages; Nywelo, Madala and Gologolo. However, there was no evidence that these villages were acting as a source of infection for the remainder of the focus. The likelihood of becoming infected with plague is highest between the ages of 5 and 19 and lowest for adult men. This was most clear in the ward encompassing the three high-incidence villages where the risk of plague among children aged 10–14 was 2.2 times higher than for adults aged 30–34, and among adults aged 30–34, the risk was 2.4 times higher for women than men.
Dengue virus infection and associated risk factors in Africa: a systematic review and meta-analysis
(MDPI, 2021) Mwanyika, Gaspary O.; Mboera, Leonard E. G.; Rugarabamu, Sima; Ngingo, Baraka; Sindato, Calvin; Lutwama, Julius J.; Paweska, Janusz T.; Misinzo, Gerald
Dengue contributes a significant burden on global public health and economies. In Africa, the burden of dengue virus (DENV) infection is not well described. This review was undertaken to determine the prevalence of dengue and associated risk factors. A literature search was done on PubMed/MEDLINE, Scopus, Embase, and Google Scholar databases to identify articles published be- tween 1960 and 2020. Meta-analysis was performed using a random-effect model at a 95% confidence interval, followed by subgroup meta-analysis to determine the overall prevalence. Between 1960 and 2020, 45 outbreaks were identified, of which 17 and 16 occurred in East and West Africa, respectively. Dengue virus serotype 1 (DENV-1) and DENV-2 were the dominant serotypes contributing to 60% of the epidemics. Of 2211 cases reported between 2009 and 2020; 1954 (88.4%) were reported during outbreaks. Overall, the prevalence of dengue was 29% (95% CI: 20–39%) and 3% (95% CI: 1–5%) during the outbreak and non-outbreak periods, respectively. Old age (6/21 studies), lack of mosquito control (6/21), urban residence (4/21), climate change (3/21), and recent history of travel (3/21) were the leading risk factors. This review reports a high burden of dengue and increased risk of severe disease in Africa. Our findings provide useful information for clinical practice and health policy decisions to implement effective interventions.

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